DE2503825A1 - DATA INPUT / OUTPUT CONTROL UNIT - Google Patents

Description

COMPAGIiIE H0HEYWELL BULL
94 “Avenue Gambetta
PARIS (20) / France

Our reference: H 1054 -

Data input / output control unit

The invention relates to a data input / output control unit, which the transfers of information between the main or central memory and the peripheral devices belonging to the peripheral subsystem. In a data processing system, processing the data requires a ongoing and simultaneous dialogue between what is referred to as aids, the main consist of large-capacity peripheral units, the main memory and the central one Processor that actually performs various calculations on the entered data.

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For the case ₁ that a central unit with a

large number of peripheral devices is connected, it is known to depend on them to summarize their characteristics in groups and to use them with device controls PCU (these are the initials The invention relates more specifically to the means for controlling transfers of information between the central unit and the Device controls. In a system of this type, the main problem arises from the speed difference between the flow of instructions in the Inside the computer on the one hand (a speed in the order of magnitude of 1 million operations per second) and the generally much slower transmission speeds on the other hand, which by the peripheral devices are imposed (ten characters per second in the case of a teletypewriter, Sixty for a strip punch, 200,000 for a magnetic tape). In the state of the art this problem has been solved by allowing the central processing unit to perform an input / output operation for as long has blocked until it is finished. Increasing the processing power of computers has one This type of solution quickly made impossible because of the time required for the data input / output is much too expensive for units of this type. That has given rise to after institutions too looking for the simultaneous execution of a processing program and input and output operations enable. Various solutions have been proposed, in particular one Operating mode known as program interruption. In this operating mode, the The central unit is relieved of the periodic overloading of the peripheral devices which it uses

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■ Interrupt to report that you are willing to do a certain job.

The interruption consists in the fact that the currently running program is temporarily stopped, so that the program executing the transfer can execute it with priority. Of course If the processing program is delayed by this interruption, the transfers of data require, however, if they have been prepared by the device control, with respect to the actual Processing only takes a short time.

The transmission of a word sets in the interrupt operation the execution of a program, which Io takes up to 20 memory cycles and of which only one only actually used. That then led to automatic exchange units or has used channels that are able to take over the transmission of a data block. the Exchange unit then issues a service request for you to have a memory cycle to perform this Exchange is assigned.

An operation proceeds as follows:

- initialization of the transmission by * the program,

- Transmission with a cycle determined by the peripheral device, and

- End of broadcast.

In this operating mode, the central processor should initialize every transmission. To the central unit to relieve, it has already been proposed to chain the data and punctures, wherein the input / output control unit or

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Exchange unit has its own program. The data chain and the function chain are different Terms. The data chaining makes it possible to automatically move from one table to one to skip others when the transfer of the data in the first table has ended. The functional chain allows several transmissions to be carried out one after the other, with the various recordings can be brought into play in one and the same peripheral device.

The invention relates to a device of the type described above, in which the input / Output control unit IOC (these are the initials

it ft

of the English expression input output controller) is a unit that an input / output control program or channel program contained in the main memory • can read, decode and execute.

The following tasks are assigned to the control unit IOC:

- Control of the central interface

- Control of access to and reading in the main memory

- Control of the execution of the program

- Feeding the program

- Control of access

- local execution of certain commands

- Chaining of the episodes on the local program.

The control unit IOC is generally divided among different channels and can have approximately 100 Execute channel programs at the same time.

To perform a task, a process may need information stored in a peripheral device,

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such as a card reader, ■

stores are. It may be the results This operation must be routed to another peripheral device, such as a Printer. These operations are controlled by special instructions called "channel commands" and output to the peripheral device by the input / output control unit. As a channel program denotes the entirety of the channel commands that are used in an input / output operation 'to be used. To achieve a better organization of the information exchange is between the input / output control unit IOC and the peripheral devices one here as device control PCU designated unit for controlling the peripheral devices, which is either a recording and control unit URC or a control unit MTC for magnetic tape recording devices or a mass storage control unit MSC, i.e. units for controlling a peripheral subsystem (device controls PCU).

The input / output control unit IOC has the task of carrying out the input / output operations between the main memory and the device control PCU. For example, you might want to give a clue to give six device controls to be connected to an input / output control unit.

The interface between the device control and the input / output control unit is called the interface Called PSI of the peripheral subsystem. It is agreed that the transmissions will be between the main memory and the device control as input

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or read if it is a transfer from the device controller to the main memory MM is involved, and is referred to as outputting or writing when it is a transfer acts from the main memory MM to the device control.

When a process requires the use of a peripheral device to perform a transfer, It "wakes up" the assigned channel program by means of a special command sent to the central processor.

In this case, the input / output control unit gives the peripheral device to be connected assigned device control sends a special signal via the interface of the peripheral subsystem, to indicate that a channel program is waiting to be executed.

According to the invention is the input / output control unit for a data processing system with a main memory, with a central processor and with peripheral units that are connected to the central processor via at least one device controller which acts on the peripheral units / with the input / output operations under the control of channel programs, characterized in that they are spatial connection channels between a device control and an input of the central processor and digital channels for connection to the central unit, a digital channel being assigned to a peripheral unit alone, designated by a channel number is, referring to the spatial channels

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and information related to the digital channels are summarized in main memory tables, the table of spatial channels from several Spatial channel entries consists of each spatial channel table entry being a table of digital channels, which consists of inputs from digital channels and reference addresses that enable access to the information.

The input / output control unit according to the invention enables optimal use of the system’s physical resources, taking up only the time required for data transfers will.

In a further embodiment of the invention, the central processor and the device control have the Ability to send messages to report events to the input / output control unit Submit, if during the execution of a Set channel program synchronous or asynchronous events.

The user programs are to be used for the transfer of data and programs can communicate with the peripheral devices. In this case, certain utilities of the processor CPU (the are the initials of the English expression central processing unit) of the input / output control unit Dedicated to IOC. The user program requests are executed with the help of a macro call, which generates a program to control the input / output channels. These channel programs are formed from a sequence of channel command inputs TCE. A channel command input consists of

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two words of main memory that contain information about control and addressing, what is in the is described in more detail below.

The input / output control unit executes and issues certain commands with the aid of the central processor CPU the others to the device controls PCU for execution. To explore the possibilities of processing Enlarging multiple inputs and outputs is every channel program with a digital channel which is multiplexed with other digital channels on a spatial channel. the User programs connect to the channel programs via semaphores, which are described below are described and which are structures that synchronize the Enable commands and data. The channel programs enable the data that Chaining of the control commands and the transmission of intermediate or final states. What here as "State" is a sequence of information relating to a particular peripheral device, which enables the central unit to change the state of the To know the peripheral device and to take appropriate measures. In a system in which the invention is applied, the input / output control unit is microprogrammed. It means that a control memory contains machine-internal programs, which consist of fixed sequences of micro-instructions, the execution of which concatenates the various basic functions, the sum of which is a function of the machine in question. In this, each function is controlled by a command and each type of instruction corresponds to a microprogram, which is formed from the sequence of microinstructions,

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- Q _ ·

requested by the command (register-to-register transfer, memory selection and reading or writing, incrementing the counter, operational control of the device, etc.). Each Microprogram corresponds to the execution of an instruction contained in the "interior decoration" or the whole the functional specifications of a system is established.

The processing of the code group of an instruction of the inner decoration calls the microprogram, which is is permanently located in the control store CSU. This control or control memory exists mainly from a read-only memory ROS provided in the central processor CPU and for which there is the possibility of expansion into a reserved zone of the main memory.

The microprogram executes the instruction of the inner decoration with the operands which are defined by the instruction code group 0PC0. All standard microprograms are in the read-only memory part of the Stored in the control memory. This control store CSU is divided into segments. The microprograms belonging to a group of commands of the interior decoration are housed in a segment. There are branching options inside the control storage unit CSU which allow multiple selections and repeated use of common sub-microroutines. The microprograms manage the entire control of the central processor by creating firmware blocks that have specific functions. These firmware blocks are related to the operating system in Connection, but they are not directly controlled by the commands of the interior decor.

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The microprograms of the input / output control unit IOC carry out the functions which are shown in the interior decoration and the functional specifications of the PSI interface of the peripheral subsystem are set. According to the invention, the peripheral devices are visible to the program, namely via a digital quantity, which is based on the hardware and as a digital channel program (which consists of a sequence of input and output control commands), and via execution states that the central processor can know based on the semaphores.

For example, the microprograms for input / output control can cover a zone of 5000 octades in occupy the control or control memory and a zone of 1500 octades in the main memory.

Theoretically, 256 digital channels can channel programs run on a single spatial (physical) channel. The practical limit depends on the Possibilities of the channel and the device control. Execution of a channel program a digital channel is intended to be viewed on a principle level as a pseudo input / output operation simultaneously with other input / output operations and with operations of the central processor is performed. Therefore, when there are twelve spatial channels, the number of input / output operations is theoretically 12 χ 256. The device control controls the execution of the channel program with help of a special control command addressed in the input / output control unit and as a service code group referred to as.

When an event occurs or when the execution

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of the channel program in the device control is finished, an event message is sent from the Device control delivered to the input / output control unit. An event message contains a Service code group and a state regarded as data information. Thus, between the Input / output control unit and the device controller transfer service code groups and transfer of data instead. The hardware and firmware components of the input / output control unit are with the intention / to control these transfers.

Further features and advantages of the invention will emerge from the following description of a particular one Embodiment of the invention with reference to the drawings. In the drawings show:

Fig. 1 is a diagram of the central processor of a

Data processing system and main memory,

2 shows a basic circuit diagram of the connection

an input / output control unit IOC,

3 shows a diagram of the multiplexing of the

Channel programs on a spatial channel,

Fig. 4 is an exploded view

the input / output control unit of a data processing system,

5 shows the scheme of a channel program,

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Fig. 6 is a diagram of the format of a channel

program header,

Figure 7 shows the structure of a channel command

Gabe CCE,

8 shows a channel command input CCE for

a data transfer,

Fig. 9 = the PSI interface,

Fig. IO is a timing diagram showing the off

represents the management of a sewer program,

Fig. 11 is a timing diagram showing the Be

represents the beginning of a data transmission,

Fig. 12 is a timing diagram showing the end of the

Represents the execution of a data transfer,

13 is a diagram of the dialogue between the

Central processing unit CPU and the device control PCU at the interface PSI,

FIG. 14 shows the organization of the tables PCT from FIG

spatial channels and tables LCT of digital channels in the main memory,

14a shows an addressing scheme for the tables

LCT of digital channels,

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Fig. 15 is a diagram of the procedure of reporting

of events

16 shows the representation of a queue

Q / MS / EVQ,

17 shows a diagram of the various to

status of the digital channels after the input / output commands,

18 shows a digital channel input LCE,

Fig. 19 is a flow chart of the notification of

Events

Fig. 20 is a flow chart showing the processing of the

News, and

21 is a diagram of the flow of urgent

interruptions.

Each device control is assigned a channel control or channel head unit CHU, which is shown in FIG. 1, each channel head unit comprising:

- a service code group register SCR »which stores the current service code group,

- a 16-octade buffer register RF, which the temporarily stores data transferred between the main memory and the device control PCU,

- A counting register L 1, which the number of octades indicates that between the device control PCU and the storage or buffer memory register RF are to be transferred, and

- a difference pointer DP, which the number of

in the register RF at a given moment

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saved octades.

The input / output control unit also consists of various components.

The channel control unit CCU contains a work counter SPC, which indicates the number of octades which are still to be transferred between the main memory and the buffer register RF of each channel head unit. The data management unit DMU contains:

a) a buffer memory OB for four octades, which temporarily stores the data read in the main memory Saves data before entering it into the RF register,

b) a buffer memory IB, which before entering the data in the main memory, the same task Fulfills.

The device controller controls the execution of the channel programs and directs the use of the spatial channels. The central.;: Processor is thus relieved of the task of constant monitoring of the CPU Peripherals relieved. It only takes part in the input and output operations according to signals, which are fed to it by the device control when there is actually something to transfer Control is achieved through a dialog at the PSI interface, which consists of sequences of data transfers and consists of sequences of service code groups.

The sequences of service code groups are used to execute 509832/0 9 21

used in the following operations:

- Beginning of the execution of a new channel program and beginning of the transmission of the first channel command input CCE of the sewer program,

- Shifting the channel pointers in the channel program and initializing the transmission of the next Channel command input CCE, -

- Transmission of the octades of the detailed state or initialization of the transmission of the octades of the State during the execution of a channel program or at the end of the execution of the same.

The service code group sequences can carry transmissions from Initialize octades between the device control PCU and the input / output control unit IOC.

As a result, these transmissions are called data transmission sequences, these octads can however be:

- Octades of data relating to a transmission of CCE data,

- Control command octads received from the input / output control unit IOC are submitted (octades of the next CCE input to be carried out),

- commands of the input / output control unit IOC, if this would like to inform the device control PCU about certain events,

- Octades of detailed state that occur during the execution of a channel program from the device control PCU are delivered. . -

The microprograms of the input / output control unit IOC control and direct all operations required by the service code group sequences and initialize, if necessary, the next octadic transmissions. According to the type of episode, the

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Device control PCU up to five octades can be issued: service code octade, digital channel number, branch argument or one of the three octades of the summarized state of the peripheral device (PSB). the The first two octades of a service code group sequence are implemented in a channel head unit CHU by the hardware received, but the firmware is concerned with the eventual reception of the last three octades.

During a service code group sequence, the IOC firmware can be called to receive the last octad that is output by the device control PCU, and during a sequence that more than two octades if the channel head unit CHU has received the first two octades.

All consequences of data transfers (data in the real sense, status or control command octad) are set off by the IOC firmware during the preceding service code group sequence and how the transmissions of chained data are carried out.

A transmission of chained data is a transmission of data blocks between the device control PCU and a system of non-contiguous storage zones. Such a transfer is through a system controlled by channel command inputs, which are summarized in a data link field DCA are. The length of the field DCA is determined by the content of the first channel command input CCE and indicated by the following channel command inputs except the last one. To this end a data chain identifier is used in all channel command inputs, with the exception of the last,

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brought to 1.

If the data link flag is set to 1 in a channel command input, which means shows that there is a data chain, the transmission only stops when the "count" is zero will. A new "count" and a new main memory address are set by the input / output control unit IOC from the next channel command input CCE ■ of the DCA field and the transfer is continued with the new address. The transfer stops when counting a channel command input CCE whose data link identifier is zero is, or when emitting a signal. TMI through the device control PCU.

The address control unit ACU contains a working memory for the addresses PA, which contains two registers PAO and PA1, which each device control PCU are assigned.

Each device control PCU has different levels of urgency for executing the channel programs assigned. In a data processing system in which the invention is used there are four Urgency levels available. Level 0 corresponds to the transmission of data with a high degree of urgency. Level 1 corresponds to a transmission of service code groups with a high degree of urgency. the Level 2 corresponds to a transmission of data with low urgency and level 3 corresponds to a transmission of service code groups with low urgency «The operations of the control system of the central Processors run at level 4,

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i.e. that the operations of the input / output control unit IOC versus the arithmetic operations of the central processor take precedence.

The input / output control unit IOC can manage the channel programs that relate to various device controls PCU obtain, multiplex and contain an emergency hardware network, by means of which can be determined which device control is connected at a certain moment shall be.

A channel program that is in progress will be interrupted when another channel program has a higher level of urgency. Likewise, a command from the central processor or a Operation of the system control unit having the priority level 4 by the input / output control unit IOC interrupted by the execution of a channel program at the request of the device control PCU.

K analprograitim

An input / output operation performed by the input / output control unit IOC and the device controller PCÜ is to be carried out is referred to as a channel program. A channel program is a real program, i.e. it is a sequence of program signals with branching ability, i.e. access to any address. Each digital channel is capable of a channel program to execute. Usually, executing a channel program on software requires only one single start command (CONNECT) and the receipt of a

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Message by means of a semaphore at the end of execution. There is complete simultaneity between the execution of the programs (or operations, processes) of the central processor and the execution the channel programs on the digital channels. The execution of a channel program is therefore a peripheral process.

A channel program consists of a channel program, beginning and from channel command inputs CCE. A channel command input CCE spans two words CCWO and CCW 1 in width and contains a control command octad indicating the operations to be performed and a flag octad specifies the execution conditions, such as: chaining control commands, chaining of data, interruptions, etc. 'a count' at every other octad and the absolute address of the transmission of data on a length of four octads. The count and the address field can also be extended by a control command be replaced..

There is a special indicator that indicates that another control command follows the control command, which is currently being executed. It is a chaining or concatenation identifier. If this If the indicator is zero, the processor knows that the instruction in question is the last instruction of the channel program. Another identifier, which is used as a data concatenation identifier indicates that the channel command input is indicated by the address and count CCE specified data transfer is not completed

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and that the transmission will continue with the count and address specified in the next channel command input are entered. So defines a field of channel command inputs the totality of the control commands in this case. The transmission of data takes place in non-consecutive zones, which are determined by the successive channel command inputs CCE of the field. the last channel command input CCE v / is marked by the fact that the identifier is equal to zero is. The device control PCU is not informed whether there is a data link, and therefore does not participate in the dialogue exchanged via the PSI interface. The normal one The data transmission rate should be maintained at the PSI interface even if a There is a data chain. The channel programs contain a program header that contains the number of the channel contains, to which the program is assigned, the digital name GiDi of the semaphore that is used for Calling the interrupt processing process in the event of notification of an intermediate or final event is used. The program header also contains the dimensions and position of a storage zone, which is reserved for the detailed status which is supplied by the device control ρCU will.

The execution of a GÖNNECT command begins the peripheral subsystem carries out the transfer operations by addressing a signal CPW, which indicates that a channel program is waiting.

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According to a feature of the input / output control unit According to the invention, it is the device control PCU that controls the execution of the channel programs. The device control PCtT starts the channel program by the input / output control unit IOC prompts the first channel command input CCE and then proceed to its execution.

The control unit IOC has two channel program pointers, namely the control command pointer CMP and the control word pointer CWP.

These pointers are shifted at the request of the device control PCU and by this shift the device controls can execute a program, reject it, or from a program pass another one. If the control command involves a data transfer, the input / Output control unit the count "and the address in the channel command input CCE. When a peripheral operation is finished, the device control PCU sends a message about the end and, the input / output control unit IOC places this message in a message queue.

The device control controls on the one hand the sequence of the channel program and on the other hand the use the spatial channel and resources by multiplexing the channel programs.

There are eight IOC software commands, all of which take precedence. Your task can be summarized as follows will:

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a) -CONNECT - This command selects a channel program, ie it controls whether the channel is in the activated state or not. If it is not activated, it will be placed in a queue. This snake communicates with a spatial channel. If there is at least one input in the queue, a special line of the interface of the subsystem is set to state 1, which is described in more detail below, in order to inform the device control PCU that at least one channel program is waiting to be executed

If the device control requests an initialization, the digital channel is removed from the queue, the digital channel number and the first channel command input are issued. When the queue is emptied is, the aforementioned line of the interface PSI is brought back to zero.

b) DISCONNECT '- This command informs the device control PCU that it should end the channel program of the corresponding digital channel. If the channel is still in a start queue, it is terminated by the input / output control unit IOC (before it has been started),

c) Further commands

The five other commands: RESUME (summarize), FETCH LOGICAL CHANNEL FLCH (get digital channel), LOAD LOGICAL CHANNEL LLCH (load digital channel), RESET PHYSICAL CHANNEL RSPC (reset spatial channel), SET OPERATIONAL OUT SOPO and DIAGNOSE CHANNEL (channel diagnosis) are used under special circumstances used.

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A special system of microinstructions enables the service code groups to be opened with high and low To analyze urgencies and in the channel head unit CHU the data transmissions between initialize the device controls PCU and the buffer register RF. It also allows the data transfer between the main memory and the register RF with high and low urgency to control. The microinstructions of the input / output control unit IOC are divided into four blocks divided according to the different levels of urgency in the execution of the channel programs are numbered from 0 to 3. :

A spatial channel is the spatial (physical) connection between the input / output control unit IOC and the device control PCU. This spatial connection consists of an interface PSI and devices that are arranged on both sides of the interface and have the task of controlling this interface. A device control PCU can initialize any number of channel programs and multiplex the use of the spatial channels.

For the programmer, a Diqita! Channel is a logical unit that allows an input / output operation to be carried out. When a channel program is executed, it is assigned a digital channel. The assigned digital channel is activated when the channel program is executed and the spatial channel is used in a time division manner. A digital channel often corresponds to a single peripheral device. However, if several functions of a peripheral device at the same time

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are to be executed, multiple digital channels can correspond to a single peripheral device. This is the case, for example, with a printer in which the characters are printed at the same time and the transport of the paper are to be carried out. From the programmer's point of view are the input / output operations carried out on different digital channels, completely simultaneous and asynchronous.

The device control divides the usage time of the spatial channels to several at the same time Perform input / output operations. The degree of simultaneity depends on the conception the device control PCU used, but the input / output control unit IOC can handle all degrees of simultaneity accept that are requested by the device control PCU, provided they are not overloaded will.

A digital channel is identified by a channel number. This channel number is as follows composed:

- an IOC number that is always zero

- (IOC f £ = /)

- a number of the spatial channel between 0 and 6 (PC τ? = φ)

- a digital channel number between O and (LC

It has the following format:

ioc ? = ¥ pc ^ y. LC dd

23

78

15th

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The information relating to each spatial channel and each digital channel is kept in tables. The spatial channel table PCT consolidates the spatial channel information in Segments called Spatial Channel Inputs PCE.

So there can be six PCE entries in the PCT table. Take the inputs from spatial channels sixteen words, numbered O through F in the hexadecimal system.

Each PCE input corresponds to a table of digital channels in which the information relating to of the assigned digital channels are combined, the number of which can be 256. Each .Table LCT of Digital channels will thus contain 256 inputs LCE of digital channels. A digital channel entry LCE always takes sixteen numbered from 1 to P. Words a.

PCT and LCT pointers allow the required information to be taken from each table. Of the PCT pointer contains the absolute address of the beginning of the PCT table of spatial channels and the number the input PCE of spatial channels. It has the following format:

PCE ■ £ == £

Absolute address PCT

O 78 31

The PCT pointer is contained in the main memory above the BAR address and in the working memory SPU.

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The pointer of the digital channel table LCT contains the absolute address of the digital table and the Entry number in this table. It has the following format:

Absolute address LCT

O 78 31

Each pointer of the table LCT is in one word the Input PCE of a spatial channel included.

An input PCE of a spatial channel is obtained by using the table PCT and the channel number PC achieved.

A digital channel input LCE is generated using the PCT pointer, the spatial channel number PC τ £ = φ , the LCT pointer and the digital channel number LC ^ =? achieved.

The input / output control unit IOC has special commands for the input and output operations, which are referred to as channel commands or channel control commands. A channel program is a system of channel commands and address information that trigger and execute an input / output sequence allow.

A channel program contains the number of the digital channel on which the transmissions are carried out will.

A digital channel can be used by different channel programs. The channel programs can also be on

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different spatial channels can be executed at the same time. The input / output control unit IOC controls this simultaneity.

The channel programs that have a particular spatial Use channel can also run simultaneously, except when they are the same spatial Are assigned to the channel. The central unit monitors this simultaneity. The channel programs are stored in main memory under BAR.

Structures of the channel programs In a channel program there are:

- a channel program header consisting of four words.

The absolute address of the first word of the channel header is used as the absolute address CPAA of the channel program designated. It is stored in a word of the corresponding digital channel entry.

- A channel control command input CCE consisting of two words, which are referred to as channel control word O (CCWO) or 1 (CCW 1).

The four words of the channel command header contain:

- the channel number assigned to the channel program,

- the level of urgency of the channel program compared to the other channel programs,

- the name GD of the semaphore to which the during messages generated by the execution of the channel program are routed,

- Information about the main memory zone in which the fault status of a peripheral device can be saved.

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The channel command input enables simple interaction with a peripheral device. The two Words contain a channel command, tags, and address information.

The input / output control unit is defined as a system of the components that are connected to the input and Issue operations are involved. In the data processing systems in which the invention is used the input / output control unit shares certain resources with the central processor and can interrupt the execution of the microprograms of the central processor at any point in time, to run their own microprograms.

The main resources it shares with the central processor are: the control store CSU, the main memory interface MIU and some digital units, which are:

- the arithmetic and logical unit (hereinafter referred to as arithmetic unit) ALU, which the operations performs on the 4 octad words,

- the data management unit DMU, which directs the transfer of data to the main memory,

- The address computation unit ACU, which the incrementing and decrementing operations of the executes absolute addresses, and

- the read-only memory control unit RCU, which directs the PCU-CSU transmissions and various control ors Contains test register.

The input / output control unit IOC has its own tools, which are in the ■

central processor CPU are housed without belonging to it. It is about:

in the main memory SPU by 33 memory locations

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four octades each, which can be used as work zones or to ' Reserve used in the data management unit by two registers of a 32-bit (4 octad) word for transferring the data between the channel head unit CHU and the main memory, in the address calculation unit ACU by 32 address positions, which are reserved for the input / output control unit IOC (two addresses per digital channel), in the special memory control unit RCU for circuits, which have the task of managing the interruptions of microprograms for the input / output control unit IOC and to execute.

Each spatial channel has a table LCT of Assigned to digital channels. In addition to the circuits it shares with the central processor, the Input / output control unit own circuits, which are:

- a channel head unit CHU for each interface PSI,

a channel control circuit CCC, the six channel head units CHU is common, and

- a channel control unit CCU.

Canal head '

An internal common interface CBI is defined. The interface CBI forms the interface between the channel control circuit CCC and the channel control unit CCU. The duct head unit CHU has the following functions:

- Intermediate storage of the data in a register ■ with sixteen digits without the intervention of the microprograms,

- Data transmission with data chaining. -

During the execution of a sequence by the central pro-509832/0921

- 3O -

processor CPU, which gives an address and a count for the data transfer to be carried out next, the main memory cycles are not executed.

The configuration is made up of different channels, all of which have the same speed to have. The channel with the least urgency must wait during the memory cycles that are used for the "Counting" of the other channels are carried out.

- Intermediate storage of the other parameters relating to the work being carried out, such as:

'. the urgency level,. the service code group,
. the remaining size of the data block at the interface

PSI,
. the mistakes,

- Synchronization of the dialog of the PSI interface with the components of the central processor CPU,

Generation of interrupt requests for the processing circuits, for example every time when four octades are available for transfer to main memory, provided the transfer is an input

- Execution of functions controlled by microprograms to execute service code groups, which are transmitted over special control lines on a 2-octad path.

Common channel control circuit The CCC circuit performs the following functions:

- Selecting the requests with high urgency coming from channel head units CHU (Emergency network),

Forwarding of the data coming from the units CHU and going to the units CHU, and

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- Storage of the connection information of the Units CEIlJ.

The emergency network receives the requests that generated by each unit CHU (these requirements being checked, i.e. for the most recent Stand). The following information is available:

- level of highest urgency (between O and 3, where O is the level of highest urgency),

- Number of the channel with the highest priority among those channels that request at this level (The urgency among the channels decreases from O to 11).

This information is sent to the channel control unit CCCJ submitted.

Channel control unit

The CCU channel control unit has the following functions:

- Selection of the most urgent level from among the Requests that may come from two channel control circuits CCC and transmission to the Special storage control unit RCU,

- Interface with the transmission path (BUS) A (for the data and the service code group),

- Review and storage of the data to be transferred Octades,

- synchronization of hardware and firmware,

- Interface with the channel circuits (the CCU channel control unit is able to adapt various definitions via the CBP interface),

- Row-like alignment of the data octads and if applicable the brands.

The emergency network of the control unit CCU :.

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It has two functions analogous to the functions that are carried out in the common channel control circuit CCC.
This is how you get:

- the highest priority level between two channel control circuits CCC,

- the number of channels of higher priority if the two channel control circuits CCC on at the same time request operations of the same urgency level (which are assigned to channel control circuit number O given highest priority corresponds to the channel head units number O to 5). This information are stored in registers RLR and ACN and used to generate the microprogram interrupts in the central processor used.

. Data networks

Two data networks align the data in rows, between the buffer memories and the main memory be transmitted.

The transmitted data are combined into words of four octades (plus parity key).

The control of the alignment depends on the address of the octad within the stored word and on the position of the octades in the buffer memory.

The bidirectional data transmission path, which is specialized in the transmission of the service code groups, enables the transfer of states if it is connected to the transfer path A, in which it is the main transmission path of the central processor. A channel unit can through the channel control unit CCU are disconnected. This characteristic is for

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Requires execution of isolated test routines.

1 shows a diagram of the central processor and the main memory of a data processing system.

The main memory MMU consists of addressable units. Its capacity can be, for example vary between 256 kilooctads and 1024 kilooctads. ■

It is connected to the central processor CPU by at least a memory gate circuit connected, which the Interface forms MIU. On the one hand, the memory MMU is connected to the address via the MIU interface. Computing stage ACU and on the other hand connected to the data management unit DMU.

The address computation stage ACU enables the transmission of the data or the commands to the main memory. It converts the segmented addresses into absolute addresses and saves the absolute addresses for the processing and transmission of data.

The address computation level ACU is with an associative Memory associated with the segment numbers that Contains access rights, the bases and the boundaries of the eight most frequently used segments.

The data management unit DMU allows data transfers into and out of main memory. She performs alignment operations on the operands and the commands, for which it makes preselections and intermediate storage.

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It acts on the input and output of data, reads and writes from Data reads out the programs and aligns them and reads certain programs in the main memory. the The data management unit is in direct connection with the channel control unit CCU.

The channel control unit CCU forms the interface between the central processor and the channel buffering unit CBU. It aligns the input and output of data and saves the parameters of the Transfers.

The channel buffering unit CBU consists of the common channel circuit CCC and six channel head units CHU. Each CHU unit has the task of creating words from four octades that come from the CCU unit originate, record and these octades one after the other to the interface PSI of the peripheral Subsystem to transmit, or to receive sequences of octades of the PSI interface and so to summarize that words are formed from four octades which are transmitted to the unit CCU will. For this purpose, each unit CHU contains a buffer memory with a capacity of e.g. 16 octades for the input / output operations.

The maintenance console level PMU enables connections to:

- the control panel S0P, which controls the of the system by the operator,

- The maintenance console SSP and the maintenance channel MC, which are not used for maintenance at the same time of the central processor.

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The maintenance console unit PMU is informed of errors, which are ascertained during the operations of the processor and defines the posture of the machine depending on the error. It also leads to finding an error required maintenance functions.

The microprogram memory control stage RCU controls the operations of the central processor under certain conditions.
In this case

- it addresses the words of microprograms contained in the CSU unit,

- it stores the microprogram word that is currently being executed,

- it controls the locks and the interruptions,

- it controls the execution stages of the microprogram, and

- it controls the execution of the firmware.

The unit RCU transfers the microprogram words from the control store CSU to the other units via transmission path A and calculates the next address of the microprogram. Each Microprogram word can, for example, have a length of four octades and can be five *. Microfunctions' control, which are in different Parts of the processor are located.

The ALU arithmetic unit performs decimal / binary arithmetic operations and logical operations on operands from four octades. It also performs the arithmetic operations at the segmented addresses, the ■ storage of the segment and ring numbers and the Accumulation operation in maintenance operation.

The synchronization stage TEU contains a clock generator,

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which supplies the various signals used by the central processing unit CPU. She controls the transmission of the synchronization pulses and defines the length of the cycles of the central processing unit CPU fixed. It also contains three timing devices that are controlled by a quartz oscillator.

The local storage unit SPU consists of a read-write memory for, for example, 96 words. It contains zones for storing the content of what is visible from the software point of view Register and the parameters of the system. It also contains work zones for each micro-program level.

The emulator is the subject of another German patent application by the applicant (file number P 24 56 578.4)

2 shows the task of the input / output control unit IOC on the basis of a simplified diagram. In This figure shows two device controllers PCU, each with several peripheral devices are connected. The two device controls PCU are each marked with the on their left side Control unit connected to IOC. The latter is with the one consisting of a central processor CPU and main memory MM Arrangement connected ..

As explained in more detail below, the central ProzesBorCPU is partially used for entering the Data used in main memory, in particular

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for calculating the absolute addresses.

It has been calculated that in a middle system the information input / output operations statistically take about 1/10 of the total processing time. It follows that the Input / output control unit IOC only works for a tenth of the total processing time. This corresponds to a loss of time to use the material.

According to one feature of the invention, the input / output control unit IOC is in the central processor CPU integrated. In this, a certain number of stages are purely input / output control units IOC. In Fig. 1, these stages are framed with a dashed line, which indicates the Bears reference symbol IOC. It is mainly the control unit CCU, the common channel circuit CCC and the channel head units CHU.

All the stages of the central processor CPU, the above have been mentioned, work with the input / output— Operations as well as all processing together. However, there are special registers for the input / Output control unit IOC has been introduced into the data management stage DMU and the capacity of the in the The memory contained in the address arithmetic unit has been enlarged. The principle diagram of Fig. 2 corresponds thus not the reality, since the input / output control unit IOC (more or less) part of the central processor is CPU.

In the following of the description, the input / output control unit IOC as the entirety of the facilities

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designated for the transmission of the information between main memory and peripheral devices. More specifically, the input / output control unit IOC will be the entirety of the facilities responsible for establishing links between the device controls PCU and the central memory interact, the input / output control unit IOC. Can, however, call the central processor CPU under certain circumstances.

An object of the invention is to provide means for dividing the resources among the input / output control unit IOC and the central processor CPU. To this end, there are as follows will be explained in more detail, a hierarchical order of the tasks and the input / output operations the precedence over the actual processing operations.

Figure 3 shows this multiplexing. In this figure it is assumed that the device control PCU has four digital channels. Channels 1 and 3 have a channel program being executed (the arrows point to CCE 2 and 3, respectively), channel 4 is in a queue and the program has not been started. Finally, no channel program is assigned to digital channel no. 2 (not shown), it is available. In FIG. 3, the device control PCU executes the channel command input CCE · £ = £ 3 on digital channel no. The device control PCU can request:

- either the removal of the next control command from channel 3,

- or the connection of digital channel no. 1 and taking the next channel command input CCE from the first channel program,

- or the start of a new program on the

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Digital channel no.4.

The PCU device controls do not necessarily have to point to the end of the execution of a control command wait. You can do the multiplexing in the middle during or at any time during execution.

4 shows an exploded view of the input / output control unit IOC. In this figure three device controllers PCU 1, PCU and PCU 3 are shown on the right, each of which has peripheral devices connected of the same kind. Each device control PCU communicates with a buffer memory RF via an interface PSI. The transfer takes place via a pointer> which is located in the main memory SPU, which is an input of a spatial in the table of spatial channels Channel PCE determined, which in turn enables a channel table to be reached in which there are digital channel entries LCE are located. The buffer memories RF are all connected to a common control circuit GCC connected, the task of which has been described above. At the output of the circuit CCC go the Data into the channel control unit and then into the data management unit DMU, from where they go to the central memory MM, which in addition to the tables of spatial channels and digital channels contains the actual channel programs that come from Channel control command inputs CCE are formed, which the work of the input / output control unit IOC to organize.

The aim of the input / output control unit IOC during a data transmission sequence is that the Transfer rate at the PSI interface is not

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depends on the device control PCU and by the execution of the chaining of data is not affected. For this reason, a buffer with a capacity of sixteen octades inserted into each PSI (CHU) gate circuit. The interface of this buffer has a width of 1 octade on the side of the device control PCU and 4 octades on the side of the central storage. The transfer rate between the central memory and the Buffer memory (e.g. 1.66 mega-octads / s) is greater than the highest transmission rate at the PSI interface for this gate (for example 1.25 mega-octads / s). The data chain is carried out by the firmware if the counting is finished at the level of the central memory, and during this execution you can Octades are transferred between the device control PCU and the buffer memory. '

During a write operation (MM -> - PCU) the octades are first from the central memory MM into the buffer memory RF and then to the device control PCU transfer.

During a read operation (PCU— »· MM) the octades output by the device control PCU are first stored in the buffer memory RF and then delivered to the central store.

The octades are between the buffer memory and the central memory during a hardware / Transferring firmware sequence called the data transfer sequence or sequence DQ. This episode (Seauenz)

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2503823

has a length of four octades. The position in the central memory where this data is are written in by an address of 20 bits, which is in a register SPA of the address computing unit ACU is located. This address is checked at the end of each sequence DQ.

The control of the data transmissions requires for each channel head unit CHU d ^ ei counters, namely:

- a first counter SPC located in the channel control unit CCU is located and that is at the level of the central memory for the channel command input The CCE that is currently running indicates the number of octades to be transmitted left over,

- Two further counters L 1 and L 2 _t which are arranged in the channel head unit CHU.

The counter L 1 is used to display the number of Octades are used that are at the level of the PSI interface for the corresponding input to CCE remain transferred, and the counter L 2 is loaded with the length of the transfer that in the following entry CCE of the field DCA is given,

The counter L 1 is then decremented by 1 each time if an octade is transmitted on the PSI interface, and the counter SPC is set at each Sequence DQ of the number of octades transferred to the central memory is decremented.

A transmission of non-concatenated data is done in the same way as the last input CCE of the DCA field. A control command or peripheral device status transfer will be like a data transfer is carried out whose parameters

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(Memory address and count) can be calculated directly by the firmware.

Interface PSI of the peripheral system (Fig. 9) It is a connection path which allows the synchronization of the information transfers between the input / output control unit IOC and the corresponding device control PCU.

There are 25 PSI signals divided into two groups are:

- the nine data transmission lines and the sixteen control lines.

The data transmission lines (DL D to 7 and P) are Two-way paths one octade wide (8 information bits and 1 bit for odd parity). These data transmission lines are used for transmission of the information octads from the device control PCU to the control unit IOC (read operation) or from the control unit IOC is used for the device control PCU (write operation). During a read operation can either be the octad of information generated in the peripheral devices or a service code group with or without associated information, and vice versa.

The service code groups are output from the device control PCU to the control unit IOC in order to -the Control the execution of channel programs relating to the device control PCU. One A set of service code groups and associated information is called a service code group sequence.

During a write operation, data that

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η c π OO 9 R are intended either for the peripheral device or for the control register of the peripheral device, or a channel control command or an IOC command are transmitted, which is issued to the device control PCU, in order to control the transmissions in the input / output control unit IOC check.

The control lines. Transmit the information via the interface, identify the consequences, terminate the transmissions, modify the presence of information in the input / output control unit IOC, reset the device control PCU to zero, allow control of the system and the organization of PSI switchovers checking or diagnosing the PSI interface. All of these lines are one-way lines,

The lines marked "I" (IN) at the end have their beginning in the device control PCU and its end in the control unit IOC. for those marked with "0" (OUT) at the end Lines, the reverse is true.

An interface PSI provides the central processing unit CPU and the device control PCU. A specific one Number of tools available, shown in FIG.

In FIG. 9, the connecting wires have reference numerals indicating signals with the following meanings have (the arrows indicate the direction of transmission):

SCI is the initialization signal of a service code group,

SEO is the output enable signal, it means the input / output control unit to receive.

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a service code group is ready. STI and STO control the data transmission at the interface.

TMI is the signal that signals the end of the transmission of the data issued by the device control Indicating information.

TMO is a signal that indicates the end of the transmission of the output from the central unit Indicating information.

CPW (Channel Program Waiting) is a signal that reports to the device control that a Channel program in the hardware / firmware of the central unit is waiting.

INW is a signal that is used to report to the device control that a command has been queued in the input / output control unit for delivery to it to become.

ISO is a signal which means that an error has been detected in the transmission sequence and which informs the device control about it.

RSO is a signal which initializes the device control and converts it to a known one State brings. In particular, it allows any dialog between the device control and the input / output control unit interrupt immediately. OPO is a signal which indicates that the input / output control unit connected to the interface is connected, is in operation. OPI is a signal which indicates that the device control that is connected to the interface is in operation. MTI is a signal which each time then the value

50983 2/09 21

if the device control is executing at least one channel program.

REI is a signal which then each time the Has value 1 if the device control has a channel program executes and receives a special control command (channel command).

DAO is a signal that allows the PSI interface to diagnose.

The input / output operations at the PSI interface are specified in channel programs, contained in the central memory and the device controller directs the input / output operation depending on the control commands contained in each channel program. The device control should thus access the channel program using channel program pointers, it executes the channel program by means of various operations such as: reading an initialization control command of a data transfer, transition on a new control command, etc.

This type of execution of the channel program is achieved man with the help of service code groups, and the control commands contained in the channel program transmitted to the device controller depending on the service code groups. The service code group can have meanings such as initializing a new program, starting a transmission of Data or repetition of an input / output control command, etc.

Fig. 5 shows the structure of a channel program, which is made up of the head of the channel program, the consists of ν ier words, of which the first word is the absolute address CPAA of the channel program

50 98 3 2 / 01-21

corresponds, and composed of channel command inputs CCE / each of two words exist, of which the first word is designated with CCWO and the second word with CCWl.

The header of the channel program contains the following information:

1. The channel number of the assigned channel program / the one from the digital channel number _; LC j ^^ / And there is a PC number, which is referred to as the number of the spatial channel, which corresponds to the hardware of a particular interface PSI. A central unit can supply up to twelve device controls with twelve PSI interfaces.

2. The urgency of executing the channel program depending on a comparison with the other channel programs.

3. The address (G- D.) of the semaphore that during specific messages are forwarded to the execution of a channel program.

4. The information indicating the zone in which the detailed states of the peripheral devices can be saved.

The format of the channel program header is shown in FIG.

A channel command input CCE relates to simple input / output information on a peripheral device. The two words contain: 1 / a channel command
2 / a "license plate" zone
3 / the address information in CCW .1.

The execution of a channel program consists of

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following different phases:

1. Connection phase. In this phase the channel program is linked to the digital channel, which it is assigned. The digital channel is enqueued in a queue of digital channels, the are already linked to their own channel programs.

2. Execution phase. In this phase, the digital channel assigned to the channel program is removed from the Queue pulled out so that the device control the contained in the channel program Can execute channel commands.

3. Final phase. The device control indicates

the input / output control unit of the central processing unit from a message reporting the end of the event.

Fig. 13 is a timing chart showing transfer of data in read mode (the data are sent from the device control to the central unit) and the exchange principle used here illustrated. The signals STI and STO control the transmission of data at the interface. The signal STI is simultaneously with the Application of the data generated on the transmission lines. When the input / output control unit the central unit is ready to receive the data, it emits the STO signal. The reception of the Signal STO by the device control causes the zeroing of the signal STI, which is the sampling and the transfer of the data into the input buffer of the input / output control unit of the central processing unit has the consequence. The fall of the signal STI causes

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in turn, the fall of the STO signal and the erasure of the data on the transmission lines.

The main features of this process of exchanging information between the Input / output control unit IOC and the device control are:

O. Its two-way character, the writing and reading

operations take place on the same lines of the interface.

1. The scanning signals STI and STO are interdependent.

2. The data is presented on the lines simultaneously with the sampling signal. This simultaneity eliminates the difficulties encountered in the prior art in optimizing the safety margin between the time of the transmission of data and the generation of the Sampling signal is to be provided.

3. The data can only be recorded in a buffer register at the end of three signal exchange processes the interface. The first exchange process corresponds to the delivery of the STI signal. Of the The second exchange process corresponds to the response of the STO signal. The third exchange process is the same the transmission of the falling edge of the STI signal. There is therefore no possibility of error because the data sampling takes place on stable data on the lines of the PSI interface.

50 98 3 2/092 1

4, These latter peculiarities cause the connection of a central processing unit with its remote one Device control does not require special care and that the connection system is controlled by the Connection length is completely independent.

The exchange process e.

The exchange of information at the PSI interface is carried out by a group of microinstructions controlled, which are contained in the memory of the device control. When the device control wants to connect to the input / output control unit IOC of the central unit they are accompanied by a PSI macro instruction, which specifies the type of dialogue to be carried out indicates.

This can in particular the initialization of a new program, the postponement of a data transmission initializing pointer, the initialization of an event message or the initialization to be of an end. The "microoperating system" of the device control performs the requested surgery.

The service code groups provide access to the content of the various channel command inputs CCE, which are contained in the main memory of the central unit. ₍

The input / output control unit receives to initiate or execute a new channel program an initialization service code group. The line CPW at the PSI interface has then

509832 / 092-1

the high signal value. The service code group is transmitted on the data lines of the interface. The various channel programs are queued and the input / Output control unit takes from the queue: the LC number from the header of the channel program which is taken out of the queue first with the greatest urgency can be seen, the channel command and the identifier, which is in the channel command input CCE of the Kana1 program is included.

The input / output control unit initializes the two pointers CMP and CWP of channel programs.

The pointer CIIP shows the first word of the first channel command input CCE, and

the pointer CWP shows the first entry PCE.

Every time the execution of a channel command is finished, the device controller issues a service code group to the channel command pointer by changing the values of the pointers CMP and CWP.

If the channel command of a first channel command input CCE is a transfer of data or if in the sequence of the service code group the shift of the channel program pointer is a shift which is only followed by the transmission of a channel command which it is a question of a transmission of data, the device control gives a service code group to initialize the transfer of

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Data from.

The transfer of data between the input / output control unit and the device controller can only be done after the device control the service code group sequence for initialization has delivered a data transmission. This results in the following initialization and execution sequence of a channel program.

The input / output control unit sets the pointer CPW to 1. '

The device control issues a service code group for initializing a new program.

The input / output control unit queues the digital channel number and the first channel command input CCE and transmits it to the device control, which the first channel command input CCE executes.

The device control then gives a service code group for moving the control command pointer away. The following channel command input CCE, which is a reading of data can, is then sent to the device control. A service code group for data transmission initialization is then used by the device control delivered to the input / output control unit. The data are then transmitted in execution of the channel command input CCE, then the Service code group to move the channel command pointer again through device control submitted.

5 0 98 32 / 092.1

The format of the channel command input CCE for transferring data is shown in FIG. The channel commands assigned to this particular channel command input CCE determine either Control operations of the device control PCU or the transfer of data between the Peripheral devices and the main memory.

The zone labeled "COUNT" gives in octades the size of the main memory area to or from which the transfer takes place will.

The next word is determined by the absolute address of the first octad of the buffer area of the Main memory for the transmission of data formed by the corresponding channel command is effected.

Fig. IO shows a time diagram which the initialization procedure of a new program and its consequences.

A service code group for initializing a new program is activated by the device control the signal CPW sent out so that the transmission of a digital channel number of a copy of the first channel command input from the central unit to the device control PCU is effected.

In the figure, the signal CPW generates the signal SCI for initializing a service code group, which generates a signal SEO and sends it to the data transmission path of a service code group via the device control to initialize a

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new program. This service code group is based on the data exchange interlocking principle, which is described above, generated simultaneously with the sampling signal TMI, which the Signal STO causes, which causes the fall of the signal TMI, which causes the recording the service code group by the central unit and the fall of the signal STO in the central unit which in turn causes the drop in the signal, SCI and the deletion of the service code group on the Caused transmission path, the fall of the signal SCI causes the fall of the signal SEO. When the new program has been initialized, the central processing unit outputs a sequence of octades, of which the first octade of the number of the digital channel assigned to your channel program and of which the second to the last octade are the first and last contained in the channel program Correspond to octades. In the figure it can be seen that · each octad is simultaneous with the signal STO is sent over the data transmission path and that the inclusion of the octad in the Device control takes place when the device control detects the drop in the STO signal, and that three transmission times on the PSI line elapse in accordance with the locking principle specified above, before the transferred data is actually recorded. During the transfer In the last octad of the channel program, the TMO signal replaces the STO signal to indicate that it is the last one in the channel program contained octad is.

Fig. 11 shows a timing diagram showing the initialization procedure of a data transmission

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is equivalent to. The service code groups for initializing data are created by the device control used to facilitate the transmission of data via the PSi interface according to the content of the previously to begin or restart information transmitted to the device controller. The digital channel number can be sent with the service code groups. or not.

To initialize a transfer of data sets the device control, the signal SGI to 1 (initialization service code group), which causes that the central unit sets the signal SEO to 1. When receiving the signal SEO brings the device control the service code group on the data line and gives the scanning signal at the same time STI. Upon receipt of this signal, the central unit generates the signal STO, which, if it is received by the device controller, resets the STI signal to zero. The trash of the signal STI, when detected by the central unit, scans the service code group and brings it to the central unit. The fall of the STI signal, in turn, calls the fall of the STO signal. The sampling signal TMI is used in place of the signal STI in the same The moment in which the digital channel number was issued by the device control will. The recording sequence of the digital channels is the same as the data transfer initialization sequence. The fall of the STO signal causes the SCI signal to fall, which causes the signal to fall SEO causes which the actual transmission of data from the device control to the central unit

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causes. The data is transmitted at the same time as the STI signal and the recording occurs when the STO signal drops.

When running a process, the following two possibilities can arise:

- certain asynchronous events take place in the peripheral subsystem.

- the channel program has affected a program fault, whereby it has the event message bit in the identification zone of the channel command input CCE.

They result in the creation of a service code group to initialize the event message. if the event notification message is not within a Event message queue can be stored, inputs the input / output control unit Signal 'ISO and prepares an instruction that informs the device control about store the message in the peripheral subsystem. When the message will be saved can, the message is assembled and stored by the input / output control unit.

The service code group is followed by the digital channel number, followed by one to three octades, represent the states of the peripheral device. These states become the event notification message accompany up to the software.

The initialization end service code groups are issued by the device control PCU to the Cause termination of a channel program.

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A digital channel number can have this service code group accompany or not. If, however, states are transmitted with this service code group a digital channel number can be sent.

Figure 12 is a timing diagram showing the poles of service code groups for initializing event reporting and for the end of the initialization according to the self-regulation principle of the exchanged Represents information. It can be seen that the signal TMI during the delivery the last octad of the sequence.

A channel program can terminate normally or abnormally. In the first Case, the last transmitted channel command input CCE marks the end of the channel program, in the second case, the execution of a channel program stops at the execution of an inter-channel command input CCE on. In one or the other of these cases, the device control gives a service code group to the central unit to initialize the termination from what the number of the digital channel LC and the Connect the transmission of summary states. The sequence illustrating the final phase of a channel program is indicated in the figure and is the same as that of the event message.

Executing the Kana! Programs The execution of a channel program requires several phases. During the connection phase, the channel program becomes a digital channel

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associated with it. The digital channel is then queued by Digital channels that are already linked to their channel programs.

The execution phase is the phase during which the digital channel is taken out of the queue is pulled out and / or the device control PCU contained in the channel program Executes control commands.

During the end phase, the device control PCU \ sends a program end message.

The appropriate Digital channel connected to it by the CONNECT command.

The CONNECT command brings the absolute address CPAA of the channel program into the input ECE of the assigned Digital channel and brings it into a queue of digital channels, all through the same spatial Go through the canal.

If at least one digital channel is waiting, line CPW is set to digital state 1.

For each spatial channel there is a queue of digital channels, which are based on their execution wait (q / LC / INI).

Each queue organizes the digital channels according to the order in which they are called by the corresponding device control PCU.

Each digital channel whose channel program has a

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Has received the start of execution is pulled out of the queue in which it was queued. When all the channels have been removed from the queue, the CPW line is rediscovered Zero off.

Concatenation

The digital channels queued Q / LC / INI are in the order of urgency of the assigned channel programs and for each Priority level brought into the order of arrival.

If the device control PCU requests the execution of a new channel program, that is the queue The digital channel extracted with the highest level of urgency is the one that arrived first (This is the rule: whoever is entered first is the first to be handed in - FIFO). The device control PCU requests the execution of a new channel program by sending it to the input / output control unit IOC issues a service code group sequence INP (start a new program). This episode is written with an octade.

A connection is assigned to each digital channel in the queue. It's a zone the digital channel input LCE, which is the number of the next digital channel (N.CCE) of the queue and contains the urgency of the channel program which is assigned to the next digital channel (PRI). ·

The connection of the head of the queue contains the number of the first digital channel of the queue and the

509832/0921

Urgency level of the assigned channel program _f which in the input of the corresponding spatial

Channel is saved. . ,

The execution of a channel program is carried out by the device control PCU by means of a service code group 'sequence controlled. The service code group strings give access to the content of the channel command inputs of the Channel program with the help of two pointers, the control pointer and the control pointer (Fig. 5).

The control pointer CMP can only point to the control word CCWO in a channel command input. This pointer is an absolute address and indicates the channel command input CCE of the channel whose Program is being executed. In one word, the input PCE is one of the channel programs corresponding spatial channel.

The control word pointer CWP can point to any channel command word within a channel program Clues. The pointer CWP is an absolute address and allows access to the content of the words CCWO and CCWT. the channel command input whose program is being executed.

The address CWP is in a word of the local memory SPU (word PAO) corresponding to the Spatial channel stored on which the channel program is executed.

Service code group sequences

When the digital state of line CPW is 1, at least one digital channel is one

509832/0921

Channel program assigned and awaiting execution in a queue Q / LC / INI.

To start executing the channel program, which is assigned to the first digital channel in the queue is provided by the device control PCU to the control unit IOC a service code group sequence called the "start of a new program" on the data transmission lines of the interface PSI from.

The control unit IOC takes the first digital channel from the queue and sends it to the device control PCU the digital channel number taken from the channel program header and the first channel command input CCE from. The control unit IOC initializes the two channel program pointers CMP and CWP from the absolute program address, which is stored in the digital channel input LCE corresponding to the channel program. Of the Pointer CMP points to the control word CCWO in the first channel command input CCE, and the Pointer CWP points to the word CCW 1 in the first channel command input or the control word CCWO in the second input according to the type of channel control command in the first input.

Shifting the program pointer

Whenever the execution of a channel command is finished, the device control PCU to the control unit IOC from a diest code group sequence to the program pointer of the channel move.

The main function of this service code group is

50 983 2/0921

in changing the values of CMP and CWP. There are numerous options:

- Repetition of the control command, CMP and CWP again indicate the same channel command input. This option is used when the device control PCU wants to restart the channel command, which she just carried out.

- normal operating mode. CMP and CWP indicate a new channel command input and are shifted forward, either by a channel command input CCE (incremental operation) or by two or more inputs CCE (jump operation).

- Salvo-wise restart, CMP and CWP are not shifted and always point to the same Channel command input to CCE. This option is used when the device control has a bursts of data transfer with respect to the channel command input it is currently executing would like to restart.

This sequence of service code groups indicates what action is taken to move the pointers CMP and CWP should follow, which can be:

- either a data transmission with low urgency without channel command transmission,

- or a data transmission of high urgency without transmission of channel commands,

- or a channel command transmission,

- Or a channel command transmission and a high priority data transmission, if a Data transmission is requested by the channel command (combined operation).

The urgency level of the data transmission is determined by the device control PCU.

- Start of a data transfer

5 09832/0921

In either of the following two cases:

- Data transmission initiated by the channel command of the first channel command input CCE of the channel program is required

- a service code group sequence of the shifting of the pointers indicates a shifting of the pointers, which is only followed by a channel command transmission, a data transmission is carried out by the Channel command requested. The data transfer can only be started after the device control PCU to the input / output control unit IOC a service code group sequence referred to as the start of data transmission has submitted.

The execution of a channel program runs as follows- ' dimensions from:

IOC ^>

CPW to 1 te.

In the assigned.

Program channel becomes the number of the digital channel and the first channel command input CCE entered

Next CCE

PCU

Start of a new program, INP Execution of the first channel command input CCE

Shifting the program pointer

Start of data transfer Execution of data transfer, CCE

Shifting the program pointer

etc.

5098 32/09 21

Channel commands

There are six types of channel commands,

- Data transfer: read / write / input

control / output control

- Control without data transfer

- unconditional branch (UCB)

- Test and preparation

- Control without data transmission (immediately)

- conditional branch (immediate): conditional normal

Branch / Index— Branch

These channel commands are all executed by the device control PCU, with the exception of the unconditional branch UCB, and the test and zeroing control command, executed by the input / output control unit IOC.

The control commands called immediate commands are identified by the presence of an identifier ("flag") characterizes which has the digital value 1. A channel command input is shown in Fig. shown.

Format of the data transmission inputs: FIG. 8 The channel commands which are assigned to this type of input characterize the transmission of data between the peripheral devices or the control registers of the device control PCU and the main memory.

The counting field labeled "COUNT" is in Octades indicates the length of the buffer area of the main memory to or from which the Transfer will take place.

509832/0921

, - 64 -

This counting field is never zero.

The absolute address in the data buffer is the absolute address of the first octad of the Main memory for the transfer carried out by the corresponding channel command.

Execution of the channel command input Each channel command input CCE contains a data chain identifier and a command chain identifier which indicate the operating mode in which it is to be executed. In the command chaining mode, the chaining flag of each input CCE of a channel program is set to the digital value zero. Each input CCE is passed to the device control PClI for execution, except when the input CCE is an unconditional branch UCB or a test that is carried out by the control unit IOC, as indicated above. The instruction chain identifier has the digital value 1, with the exception of the last entry CCE of the channel program, in which it is zero.

In the data chaining mode, the transfers of data blocks are chained without interruption, even if the sources and destinations of these blocks are in the central memory do not adjoin each other. The data blocks are concatenated by taking a group of channel command inputs CCE is used, which are located in a concatenation field DCA. The inputs that are in the DCA field are data transfers of branches or test control commands alone.

509832/0 9 21

Each input CCE defines the transmission of a data block. All transmissions should be in the DCA field be of the same type, i.e. mean writing or reading.

In each channel command input CCE of a data link field DCA, the link identifier brought to the digital value 1, except in the case of an unconditional branch (i.e. the Case in which the identifier is unknown), and in the last entry CCE of the field DCA, whose identifier has the digital value zero. The command chain identifier is in every entry CCE of the field DCA (field of concatenated data) on the digital value 1, with the exception of the last entry.

Just the first input CCE to control the transmission of data is transferred to the device control PCU. The device control PCU, which is based on this way via data transmission in chained operating mode (writing or reading) has been informed, the field DCA regards only an ordinary channel command entry. The other channel command inputs are carried out by the input / output control unit IOC. The transmission is terminated when the control unit IOC sets the TMO line to the digital value 1 is set or when the device control PCU generates a signal on the TMI line. In a channel program there are channel command inputs and fields DCA that are executed together.

Event notification messages;

Fig. 15 shows the different types of

509832/0921.

News and its localization.

During the execution of a channel program, the device controller PCU and / or the control unit IOC may generate event reporting messages relating to events which have occurred in. The control unit IOC or in the device controller PCU.

The information contained in the messages consists of a summarized status of the device control PCU (PSB No. 1, 2 and 3), a summarized status of the control unit IOC, parameters relating to the execution of the channel program and the. Subject of the report. There are two zones in each LCE input (see Fig. 18) and one in each PCE input, which are used to temporarily store messages between their transmission and:

- either the execution of simulated operations V, which will be executed later with the semaphores,

- or the execution of the command FLCH (extraction from the digital channel) to retrieve the messages from them Zones to be taken.

There are three categories of input / output events.

Category I.

Events that relate to the execution of channel programs and those associated with the execution of these Programs are synchronized. This category includes:

the intermediate events that relate to the execution of channel command inputs in which the event message flag is set to the value 1.

50 98 32/0921

The inter-event reporting messages are generated by the device controller or the device controllers PCU generates when the channel commands are sent by the devices * - control are carried out, if not, they are carried out by the input / output control unit IOC generated.

End or termination events The end of a channel program can be normal (end of program) or abnormal. The normal termination is controlled by the device controller PCU, and the abnormal termination is controlled by the device controller PCU or the control unit IOC.

These report messages are always stored in words 8 to 11 of the digital channel entry (cf. Fig. 18). These messages are set to semaphores G.D. by simulated operations V. the Address G. D. is stored in the heads of the assigned channel programs.

Category II

Attention events are events that are not directly with the execution of the channel programs linked and not synchronized with this version, although they relate to the device controls Obtain PCU. The warning events are always generated by the device control PCU and they are stored in words 12 to 15 of the corresponding LCE entries. Simulated operations V allow them to be set on semaphores G D. The system address G_ D is entered in a field LCE for the Command LLCH (loading the digital channel) entered.

509832/0921

Category III

Channel exception events are events that indicate changes in the operating conditions of the effect spatial channels or the control unit IOC. These messages cannot get through the control unit IOC are generated. They are always in words 4 through 7 of the appropriate Input PCE of the spatial channel saved. Simulated operations V allow them to be on one Semaphore G D to set, its address in a field of the base of the system CHX in the central memory is stored.

The intermediate event messages are issued by the device control PCU each time if the event message indicator is set to the value 1.

An attention message is sent through the device control PCU in the control unit IOC addressed each time an important asynchronous Event occurs when executing the program in the device control PCU.

In both cases the device control PCU interrupts the execution of the channel program and outputs a service code group sequence to the control unit IOC, which is formed from:

- a code group for initializing the reporting of events,

- the number of the digital channel corresponding to the channel program,

- a summarized state (from a maximum of 3 octades).

509832 / Q921

These exchanges run as follows

IOC <> PCU

^ Shifting the service code

group sequence program pointer

New channel 1 ^, execution of the new entry CCE.

failed input if the event message pointer is equal to

1 or the occurrence of an asynchronous event start of an event message LC Status summary

The status summary can consist of three octades of the status of the peripheral devices: PSB 7 * = ^ 1 PSB ? = Φ 2 PSB φ = φ 3

The PSB T ^ 1 can have two formats: Intermediate format and attention format.

PSB No. 2 and 3 are for device control PCU specific.

All three are entered in the channel command input ^ the input LCE of the program channel in the words B and F.

End of the execution phase of a channel program When the last input CCE of the channel program has been executed, the device control PCU must decide whether or not it gives a detailed status to the control unit IOC.

IOC ^ ^. PCU

^ Shifting the program pointer

Last entry CCE ^ - Execution of the last entry CCE

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Initialization of the transmission of the detailed status

Transmission of the detailed status.

This detailed status consists of an octad of the status of a peripheral device PSB j ¹ = ^ 1 of the intermediate type, as in the case of the combined status, and of a number of octades PSB which can vary depending on the device control PCU.

The detailed status is stored in the central memory. The one in the head of the channel program The detailed state entered indicates the number of octades of state that the device controls PCU should deliver, and the addresses of these octades in the central memory.

A channel program that has been executed normally or has been interrupted in the event of a fault is always ended by an end phase. During this phase, the device control PCU issues an end of execution message to the control unit IOC by means of a service code group sequence which is referred to as the start of completion.

This service code group sequence consists of:

- a termination start code group

- the digital channel number LC ^ = φ according to the channel program,

- possibly a summarized state of three octades.

The summarized state includes a first

50 98 32/0921

Octad that can take two formats: a "normal termination" format and an "abnormal termination" format, for which there are three cases: recoverable or irrecoverable disposal and manual intervention.

The octades PSB No. 2 and 3 are specific for the device control PCU and are included in the input of the digital channel corresponding to the channel program registered.

The IOC commands

During the execution of a channel program, the input / output control unit IOC can issue of information to the device control PCU, for example in the case in which an error has been detected. That is the job of the IOC commands. To send an IOC command to output the device control, the control unit IOC brings the line ISO or the line INW (Fig. 9) to the digital value 1 and waits for the device control PCU to send you a "IOC command start" supplies service code group sequence designated. The control unit IOC generates the ISO signal every time the IOC command to be issued is executed of the channel program is an asynchronous command. The "arises in the case where there is an error has been established, or in the case in which the for the summarized state the·. Digital channel input reserved fields. are occupied by octades PSB and not for the Recording of a new summarized state are available, which the device control

50 9832/09 21

PCU wants to save by issuing one of the service code group sequences: start of reporting events or start of program end. The IOC command referred to as STACK informs the device control PCU that it should temporarily put the sequence and the summarized status it contains in a stack .

The control unit IOC generates the signal INW every time an asynchronous command is to be issued to the device control PCU. This happens in the following three cases: DISCONNECT command
When the central processor CPU executes a DISCONNECT command to abort a channel program, the control unit IOC generates a DISCONNECT command, which is issued to the device control PCU, with the digital channel number corresponding to the aborted channel program, the execution of which enters the final phase.

The DISCONNECT command, like the following commands, are input / output commands. These are software commands that are part of the channel programs.

RESUME command

When the device control PCU executes a channel program after receiving a command "SUSPEND" has suspended, the central processor CPU executes the suspension Resume channel program, issue the RESUME command. The input / output control unit IOC then generates a RESUME command. This IOC command

509832/0 9 21

is sent to the device control PCU together with the digital channel number corresponding to the suspended one Channel program issued and the device control PCU must execute the channel program resume.

The control unit IOC has previously issued the IOC command to the device control PCU.

STACK command

When the fields reserved for the summarized state in a digital channel entry are free, this summarized state, which is set in the device control PCU after the STACK command is stored, can be sent to the control unit IOC, which sends the UNSTACK generated, which is sent to the device control PCU. The fields of the "summarized Status "can be freed in two ways:

a) by the IOC command, extracting the digital channel (FLCH);

b) the central processor analyzes the status between the execution of two commands of the signal PRR related to the system controller. If PRR is 1, at least occupied an octad of the summarized state its zone reserved in the input LCE and the central processor CPU frees all other status zones from the digital channel inputs.

Various channel programs can be run on any spatial channel. Different IOC commands which generate the signal rise of the line INW of the interface PSI and

509832/0321

assigned to their channel programs waiting at the same time to be transferred to the corresponding device control PCU.

The digital channels related to the waiting IOC commands are queued Q / IiC / INW brought. It's a snake pro spatial channel available. Each line puts the digital channels in the order of arrival of the assigned IOC commands. When an IOC command is issued to the desired device control PCU has been, the digital channel is pulled out of the queue. When all digital channels have been pulled out of the queue, the line INW is reset to zero.

Concatenation

The digital channels of the queue will be Q / LC / INW ordered according to the order of arrival of the associated IOC commands. When a second IOC command is assigned to a digital channel that is already in the queue, the digital channel retains his original position and will not be queued a second time.

Unlinking

When the device control PCU emits an initialization sequence of a service code group, it receives the IOC command associated with the first digital channel enqueued is.

The digital channel is then removed from the queue. *

509832/0921

If a second IOC command has been assigned to this digital channel, this will only be then removed from the queue when the two operational code groups are sequenced by the control unit IOC have been received.

Connections of queues

Each digital channel is assigned in the queue by a connection. It is about a Zone in the digital channel input LCE that contains the number of the digital channel following in the queue contains (next channel number) NL (see. Fig. 18). The head the queue contains the number of the first digital channel in the queue and is in the appropriate input of a spatial channel (PCE) entered.

Multiplexing of Diqita! Channels Different channel programs, which are assigned to the digital channels, can be executed at the same time. The device control PCU controls the use of a spatial channel by multiplexing.

The transition from one channel program to another channel program (from an operational standpoint off) is executed by the device control PCU, which has a service code group sequence which contains the number of the digital channel assigned to the new channel program. In this case, the execution of the first program is interrupted and that of the second begins.

509832/0921

- .76 -

During the execution of a channel program, ■ the pointer CMP in the input PCE and the pointer CWP in a local memory (address Pad Word PAO) is entered according to the spatial channel on which the data transmission is carried out will. If the channel program is interrupted to allow another program to run, the pointers of the first program are stored in a special zone of the digital channel entry. The pointer CMP of the new program is changed from the input LCE to the input PCE of the spatial channel and the pointer CWP of the new channel program is from the input LCE on handed over to the central store.

Case of data transfers

The device control PCU can interrupt a data transmission so that another channel program can run. During a data transfer, the control unit saves IOC for each octad transferred: ^v

- In the local memory PA 1, the absolute address of the octade in the main memory, which is in a word has been transmitted, corresponding to the spatial channel in which the transmission of Data is executed,

the number of octades remaining to be transmitted in the word of a working counter SPC, accordingly the spatial channel on which the data transfer is carried out.

If the transmission of data is interrupted, preserved the control unit IOC in the input of the appropriate channel on:

50 98 32/0921

- the pointers CMP and CWP

- the absolute address in the central memory of the last octade transmitted, i.e. the data address

- the number of octades left to transmit. That is the residual value.

If after the interruption of a channel program the data transmission is to be resumed for another channel program, the Pointer, the data address and the remaining count value are taken from the digital channel input LCE and put into the input of a spatial channel (CMP) or in the address input (CWP and data address) or in the work counter (residual value).

The operation code group sequence "data transfer start" is used to control data transfer used.

For this purpose, the octad contains the service code group a bit which indicates whether data transmission is starting or being restarted.

Case of the transmission of a detailed status As in the case of the data transmission, the transmission of a detailed status can be interrupted by a channel program assigned to another digital channel and then summarized. If the transmission of the detailed status is interrupted, only the data addresses and the remainder are stored in the corresponding digital channel input.

The service code group sequence "start of transmission

509832/0921

of a detailed status "is used to control the status transfer. One bit of the Octade indicates whether the transmission begins or continues.

Transmission of bursts of data or detailed states;

When a device control PCU interrupts the transmission of data or detailed statuses and then restarted to optimize the use of resources, the Data or status block divided into one or two parts. Any part of the block that starts with a partial transfer related, v / ird as Data or status salvo called.

Retry to transmit a burst of data

When the transfer of a salvo is finished, the device control PCU can start the transfer again try. The parameters for the new attempt are set at the beginning of the transfer of the salvo in reserved zones of the corresponding entry of the spatial channel. These parameters are:

- the pointer CWP

- the remainder of the count

- the absolute address of the first octad of the transmitted salvo.

A pointer shift sequence is used to restart the transmission of a data salvo. It is not possible to withhold a data transfer again.

509832/09 21

A semaphore is a structure of data that essentially consists of a counter SCT and an or - corresponds to multiple pointers and is used to relate a process and an event that do not occur at the same time.

An operation P carried out by a process with a semaphore enables the existence of to insure an event. One with Running a semaphore allows operation V to be aware of the presence of an on an event the waiting process.

Certain firmware blocks have the option of generating special messages for the processes and the channel programs which form pseudoprocesses can be transmitted. Operation V, which is executed by the firmware blocks to transmit a message is called a simulated Operation V denotes. In the special case one simulated operation V, access to the semaphore is obtained through its system name G.D, while in the conventional operations P and V the access to the semaphore by means of a semaphore description is obtained.

16 shows the queue Q / MS / EVQ and FIG. the queue processing flowchart * When event reporting messages are generated and stored in the appropriate LCE and PCE inputs put them in a queue, in which they are waiting, by commands FLCH or by a simulated operation V to be taken. For the control unit IOC and all spatial

50983 2/0921

Channels is only a single queue Q / MS / EVQ available. If at least one message is waiting in the queue, the PRR signal is on the value 1 is set (phase 200 of FIG. 20). PRR = O means the queue is empty. The messages are placed in the queue in the order they arrive.

16 shows the structure of the queue Q / MS / EVQ. The word 3 of the auxiliary memory SPU gives with the address of the head of the queue in the first two octades and the Address of the tail of the queue. The memory zones of the inputs of digital channels and spatial channels containing the messages in queue Q / MS / EVQ constitute the Tail links. A half-word field in each connection NL contains the relative address the next link with reference to the PCT table.

These relative addresses are: - the address of word 4 of an input PCE (connection the channel exception report message) or the address of word 8 of a digital channel entry LCE (connection of intermediate or termination notification message)

or the address of word 12 of a digital channel entry LCE (connection of attention alert message).

These relative addresses are multiples of 16, making the four negligible bits Are zero. In the half word of a connection that is used for the relative address of the next connection

509832/0921

is reserved, the four bits are disregarded. Bits 14 and 15 indicate the Type of relative address. If these bits are 0 or 1, it is relative Word 4 address of a spatial channel input PCE. If they are 1 or O, it is the relative address of word 8 of an input LCE, and 1 or 1 respectively the address of word 12 of an input LCE. In Fig. 16, the head of the queue shows the word of the memory SP to the word 8 of the input LCE 1 of the table LCT O, which is to the word 8 of the input LCE of the table LCT 2, which refers to the word 4 of the input PCE 4, which in turn refers to the Word 12 of entry LCE 0 of table LCT 1 shows which in turn points to the word 12 of the input LCE .1 of the table LCT O, which is empty.

The output of the queue q / MS / EVQ can be carried out as follows. In Fig. 20, if PRR = 1, there is at least one message in the queue (204). This message can removed from the queue by an input / output command FLCH (extraction of the digital channel) will. The PRR signal is transmitted by the control device between two commands from the central processor of the system tested. When the PRR signal is 1, the microprogram currently running becomes interrupted and the request processing stage carries out a simulated operation V (205). until the queue is emptied and until the · PRR signal is brought back to zero. A microprogram break is defined like a lock. The simulated operation V has several functions:

509832/0921

- Removing a message from the queue Q / MS / EVQ, the first to be removed Message is the first message entered.

- Try to put this message on the corresponding semaphore, which is in Depending on the message to G D G D. or

a a ι ι

DG acts (phase 207). If this attempt is successful (208), the message is removed from the queue and appropriate inputs PCE or LCE and placed on a semaphore. If the message cannot be placed on a semaphore due to the lack of free communication links (209) in the corresponding segment of the memory SP, two cases (210) are possible. If the message is of the intermediate, termination or caution type (211), the message is taken from the queue Q / MS / EVQ and placed on a semaphore of free connections (GD) or (G ₀ D) of the segment SD brought, which is originally assigned to the message. The message remains in the storage zone of the corresponding input LCE. All of these messages assigned to the semaphores of free connections form a new queue Q / LC / FLS.

If it is a message reporting a channel exception (212), the message will be taken from the queue Q / MC / EVQ and the memory zone of the entry PCE (word 4). the Message is posted by the request manipulator and by the exception manipulator recorded (213, 214) ..

If during a simulated operation V a

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System exception other than the absence of free connections of the semaphore G D is generated (215), the message in question is made by the simulated operation V out taken from the queue Q / MS / EVQ, but remains in the entry LCE or PCE (216). The message is picked up by the exception manipulator (217).

The structure of the queue q / LC / FLS of the semaphores of free connections has not been shown. It is almost identical to the queue Q / MS / EVQ, with the exception that the connections of the head of the snake and the tail of the snake are in word 2 of the local memory SP. When operations P make connections available in the segments SD, the corresponding messages are taken from the queue Q / LC / FLS and placed on their semaphores G ^ D ^ or GD and out of the zones of registration

el 3

Taken from the LCE in which they were registered.

Figure 17 is a diagram showing the various states of the digital channels and the transition from one state points to another state.

Input and Output Channel Operating States During the execution of a channel program, the spatial channels and the digital channels are characterized by a certain number of states.

States of the spatial channel

At a certain point in time, a spatial channel in the non-operational state or in the operational state be.

50 983 2/09 21

A spatial channel becomes inoperative when the signal OPI or OPO (Fig. 9) of the interface PSI assigned to the spatial channel based on the determination an error or the detection of malfunctions is set to zero.

A spatial channel goes into the operational state when the signal OPI and the signal OPO pass one of the following commands of the central processor can be set to the digital value "1":

- Command for setting the spatial channel

(RSPC)

- Command to reset (SOPO)

Diqitalkana! States

At a certain point in time, a digital channel has one of the following states:

- available (AVL), queued (ENQ), active (ACT), waiting for the message of the End (TNP).

In the "available" (AVL) state, a digital channel has finished the previous program and is free for starting a new program. In a queue (Q / LC / INI) it is at the beginning in the "available" state now a new channel program by a Input / output command CONNECT assigned.

A digital channel is removed from the queue in one of the following cases:

- the device control PCU starts executing the assigned channel program and the digital channel goes into the active state (ACT),

509832/0321

a DISCONNECT or RESUME command is executed before the device control PCU receives the assigned Channel program begins. To the DISCONNECT command it goes into the state "waiting for the message of the end",

- when an RSPC or SOPO command is executed and there is no event reporting message for occupied positions provided for this purpose in the digital channel input LCE, the digital channel goes in this case to the "available" state (AVL).

Active state

A digital channel is in the active one during the execution of the channel program assigned to it State.

A digital channel goes into the active state ACT when it comes out of the queue Q / LC / INI of the corresponding digital channel is taken and if the device control PCU the assigned Channel program begins. A digital channel exits the active state ACT in one of the following cases:

- when the central processor CPU or a DISCONNECT command is executing the channel program terminated, to which, if necessary, a transmission of a detailed States. then the digital channel goes into the state "Waiting for the message of the Endes "(TNP) over.

- If the signal OPO of the PSI interface drops to the digital value zero, then a RSPC or SOPO command executed and no event notification message takes up the reserved zones

50 9832/0921

LCE in the corresponding digital channel entry. The digital channel then returns to the state "available" (AVC) back.

"Waiting for the end of message" (TNP) states A digital channel is in this state when an end-of-message message occupies the zones reserved for it in the corresponding input LCE after the appropriate channel program has been fully executed.

A digital channel can assume the status TNP in two ways:

- The digital channel is in the active state ACT and the device control PCU issues a sequence of termination start service code groups after the end of execution of the associated channel program and transmits the detailed status if necessary.

the digital channel is in state ENQ (queued) and on DISCONNECT or RESUME command is being executed.

A digital channel leaves the TNP state and takes the AVL availability state in one of the the following cases:

- The content of the LCE zone reserved for the event reporting messages is simulated by a Operation V or cleared by a digital channel assignment command FLCH,

- when an RSPC or SOPO command is executed, while no event notification message occupies the corresponding zones.

50 98 3 2/0921

The event reporting messages During the execution of a channel program, the device control PCU and / or the input / output control unit IOC can send out event reporting messages ENM. These messages contain information relating to the events that occur in the device control PCU and / or the control unit IOC.

This information consists of summarized States * of the device control PCU (PSB No. 1, 2 and 3), summarized states the control unit IOC, parameters relating to the execution of the channel programs and the circumstances of the report that is the subject of the message. There are two zones in each entry LCE and one zone in each entry PCE, which are used to temporarily store the messages between being sent by the control unit IOC or the device control PCU and:

- either the execution of simulated operations V, which take place later to put the messages on semaphores, by their name GD are specified,

- or the execution of the input / output command "Extraction of the digital channel (FLCH)", which is entered in order to clear the relevant zones.

There are three categories of input and output events. ■ 1) - Events related to the execution of channel programs and those related to this execution are synchronized. It is a matter of:

509832/0921

f Intermediate events that relate to the execution of channel command inputs CCE whose flags have the digital value 1,
- termination events,

the end of a channel program gives, under normal conditions, a normal termination, the end the execution of a program before its normal interruption due to an abnormal condition results in an abnormal termination.

Termination event messages are sent by the device controllers PCU for normal terminations and sent by the device controls PCU or the control unit IOC for the abnormal terminations.

All of these messages are in the same zones of the corresponding input LCE (words 8 through 11, Fig. 18). The simulated operations V put them in a queue on semaphores, their names G. D. in the heads of the assigned channel programs are included.

2) - "Attention" events

Events that are assigned to the device controls PCU, but without a direct relationship to the Execution of the channel programs that are not synchronized with these executions. They are called Denotes Caution Events.

The corresponding messages EMN are issued solely by the device control PCU. she are always stored in the same zones of the corresponding input LCE (words C to F, i.e.

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13 to 15 in Fig. 18).

The simulated operations V bring them to a single semaphore (G, D), the in a

3 3 _

Combined field of the "Load digital channel" (LLCH) command in a combined Field of the corresponding entry LCE is entered.

3) - Exceptions from channels

These are the events that lead to a change in the operating status of the digital channels or the input / Include output control unit IOC. These events are not related to the execution of the channel programs synchronized. The corresponding messages are always from the input / output control unit IOC submitted and in the same zones of entering the spatial channel (words 4 through 7) registered.

A simulated operation V queues you on a single semaphore, its Name (G D) is entered in the exception cell of the base of the system (address in the central memory BAR + 2 C).

There is another facility through which external events are associated with processes in the central processor can. If this connection is required, a request will be made by the Circuits and the microprograms of the data processing machine via an "event query system" designated arrangement submitted. These

5 0 9 8 3 2/09 21

Request is checked between the processing of commands of the active process, which controls the central processor, and this results in a simulated operation V, which this active process the Transmitted information which concern the external event. These external events that are processed between commands are not directly linked to the active process, which controls the central processor. In particular, these events are input / output interruptions or certain exceptional states.

The event polling system allows communications related to input / output interruptions. Input / output interruption is understood to mean any communication that occurs from the input / output subsystem. That includes the communications coming from the input / output control unit IOC and from all peripheral devices.

The input / output subsystem controls the asynchronous input / output operations and ensures a high degree of overlap with the operations carried out by the central processor. That The input / output subsystem thus contains the system of all the facilities required for the Transfer of information between the main memory and the central processor as well all peripheral devices are required, which are provided in a peripheral subsystem are.

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Due to the fact that the input / output subsystem IOC and the data processing subsystem CPU working independently during the execution of a channel program, multiple events can occur occur which are to be communicated to the central processor. As these events during the execution or at the end of the execution of the channel program, the latter becomes interrupted and the input / output subsystem delivers an event reporting message containing the number LC corresponding to the channel program.

These input / output message messages can denote the following events: First of all those events that are linked to the execution of the channel program and those in the following are referred to as intermediate or termination events, and secondly, those events which, although one are assigned to certain peripheral devices, but which are not directly related to the execution of the channel program and which are referred to below as attention events, thirdly those events which result in a change in the operating states of certain input / output circuits in Are related and the following as exceptions (special features) of a spatial channel or exceptions (special features) of a bad input / Output mode.

Input / output event messages are sent to a process in the central processor in the following Way reported. When an input / output message is recognized, it is used as an event query system called arrangement requested to execute a pseudo process. This arrangement directs a

50 983 2/09 21

simulated operation on a message semaphore, converting the message to a Process can be transferred in the central processor. The input / output interruptions can thus be viewed as processes in the same sense as the Processes in the central processor. That means that they deal with the processes of the central Processors using message semaphores and simulated synchronization primitives. Also transmits the simulated operation V the message in favor of the digital channel, just like an instruction V the Transmits message in favor of the process in the control of the central processor. For input / Output Interrupt, the input / output subsystem supplies a signal which a memory element positioned, which is, for example, a specific bit in a register location, which indicates that a message was generated by an input / output event. This Special signal is recognized by the central processor as a signal indicating that a Event reporting message waiting to be queued on a semaphore. This memory element, which has been positioned, is hereinafter referred to as an interface memory element designated. When this interface storage element is in the "one" state, know the central processor that a simulated operation V is to be carried out. At the end of the the command being executed becomes the event query system represented by the flowchart introduced by the central processor.

The event query system consists of a spatial

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Facility that has the task of performing a group of operations as shown in the flowchart. This system can be known from Circuits or microprograms can be built.

The event query system is activated by the central processor at the end of the execution of the current command introduced by the active process.

The flow chart in Fig. 19 shows that the system 100 for processing input / output events is introduced when the event query system detects the presence of a waiting message via input / Detects output events. That can be indicated by the interface toggle that is in the "one" state and is in turn an entry into a digital channel queue has queued for an event, i.e. the queue Q / LC / EVQ shown in FIG. These event messages should be queued at a message semaphore, whichever is in the main memory of the central processor CPU. Before the functions are described executed by the system 100 to process input / output events, 18, the tables used by the input / output control unit IOC and the simulated one will be described with reference to FIG Operation V concern.

If. Event reporting messages by the control unit IOC have been generated, they are stored in a suitable digital channel table LCT, which contains several digital channel table entries LCTE, one of which is shown in FIG. 18th

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is shown. Each input LCTE contains an event reporting message which is to be transmitted to a process in the central processor by means of a simulated operation V. Each entry LCTE can contain two data words in the event message queue Q / LC / EVQ (FIG. 16). There is a single queue Q / LC / EVQ for all digital channels of the control unit IOC. When at least one message has been presented, the queue is formed and a signal is sent which places an interface storage element in the "one" state and identifies the occurrence of an input / output event. When the queue is empty, there is no signal and the storage element is set to the digital "O" state. When the cut _; Digit toggle is in the digital "one" state, the event query system allows as many simulated operations V to be performed as necessary to empty the Q / LC / EVQ queue, after which the interface toggle is reset to the digital "0" state.

The data sent by the input / output subsystem to the Entering LCTE messages delivered are in the queue q / LC / EVQ in the order of their Arrivals arranged, i.e. in the order FIFO (first in - first out). Every simulated operation V performs several functions on the queued message. First of all, she takes the initial message of the reporting of events of the queue Q / LC / EVQ. Second, tried the simulated Operation V to queue this message on the associated semaphore identified by the semaphore system name is given, i.e. by G., D. for the

50 98 3 2/092 1

Intermediate or completion messages and by GD for the attention message, or it tries to deliver the message to a waiting process identified by this semaphore. Third, if the message can be queued at the semaphore or delivered to a waiting process, it is taken from the queue Q / LC / EVQ and the appropriate storage area of the corresponding entry LCTE. Fourth, if the message cannot be queued at the appropriate semaphore because there is no free communication link in the corresponding segment SD, it is removed from the queue Q / LC / EVQ and linked to the semaphore of the free connection of the segment SD which corresponds to the semaphore (G., D.) or (G. D ₌ ) initially assigned to the message. The message remains in the memory zone of the entry LCTE, but the message links are changed, ie those entries LCTE which are assigned to the semaphores of free message links are added to a new queue Q / LC / FLS, ie the queue of digital channels the semaphore of free connections. The organization of the two queues Q / LC / EVQ and Q / LC / FLS can be understood more easily from the description of FIG.

The input / output control unit IOC uses specific Tables, one of which corresponds to the various digital channels that connect to the Establish main memory. The input / output tables are arranged after the absolute address O, but above the base address register (BAR). The in Fig. 16 The input LCTE shown is an input to the digital channel table LCT such as that shown in FIG are.

50 98 3 2/0921

- 96 - ο cn ^ O ^ Γ _%

I OUOO L

Each digital channel table entry contains 16 words and it is used to store the information relating to the digital channel, plus the information relating to the channel program, the intermediate message or flag the event termination message and the attention messages. Alone those Fields of the input LCTE which are suitable for the invention are described below. The information, which are dependent on the program are stored in word no. 1 and they contain the status of the digital channel LC in the first byte and the attention semaphore names G_, D_ in octades 1 to 3 of the

Cl Cl

Word No. 1.

The intermediate or event termination message to be transmitted is shown in words 8-11. In particular are the first two octades of word 8 the identifier of the following connection NL, which the Identifies the queue in which the digital channel table entry is located. As already described above, this can the event message queue will be Q / LC / EVQ, which appears when a message is first sent to the table is transmitted, or a queue of semaphores of free connections Q / LC / FLS resulting from the impossibility the result is to store the message on the appropriate semaphore. Octade 2 of word 8 indicates the type of Corresponding to a connection field for the input / output operations. The connection field indicates the way in which the input / output operation is to be terminated, and it may also contain information which involve normal or abnormal termination. In the fourth octad of the word 8 is the first half of the byte indicates the urgency of the message that is described in the input / output operation Urgency of the channel program. When this message is put in a message semaphore, whose queue is determined by urgency, the field identifies the position of the message in the

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Snake Q / M / S. The next half byte is the message type / which indicates the fact that this message resulted from an input / output operation. The word 9 entering LCTE contains specific information that identify the number of the digital channel LC and other information that the invention is not concerned. The word 10 contains the identifier of the channel command input CCE which generated the message about the notification of intermediate or termination events. Word 11 may contain the state of the input / output device and the input / output control unit.

Words 8 through 11 form the message that is sent by the simulated operation V to a system address semaphore G., D. is to be transferred. Words 12 to 15 form an attention message that is fed to a semaphore which has a system address G_, D_, which is identified in word 1 of table LCTE *

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The first half-word of the attention message contains a field for the following connection, which its position in the table LCTE and also indicates whether it is a queue Q / LC / EVQ or Q / LC / FLS acts. The explanation field, i.e. octad 3 of word 12, contains a predetermined one Completion message represented by the code group lOOÖllOl. The field indicates this semaphore message as a caution-type message. The urgency field which consists of the first four bits of the fourth octad is set to a code group 1111, the indicates the greatest urgency. The message type is the same as for the intermediate or Completion message as it indicates an input / output message. In the word 13 are the the first two bytes are the same as in the previously described messages. The last two However, bytes identify the name of the facility that delivers the attention message. Due to the Fact that an attention message is an event describes which one is assigned to a particular peripheral, but not during after executing the channel program the remaining count fields and the current address are LCTE, which are generated by the intermediate or termination event not required. However, the name of the peripheral device is required and the word 13 indicates it. The word 15 is the same as the word 11 described above. For the attention messages, all required information in just three words (words 12, 13 and 15). Word 14 is thus used to store the one associated with the intermediate or termination event Semaphore is used, which is thus in

509832/0921

the last three bytes.

Each input described in this way is LCTE first forms one or two objects in the event reporting queue Q / LC / EVQ, ie. Attention messages and / or intermediate or termination messages. Each entry represents the entry of Input / output events represent the one communication with a process in the central Require processor. This communication can be through words 8-11 or words 12 to 15, depending on the type of event to be reported. For an intermediate or termination message, the simulated operation V is sent to the semaphore G-, D.

JL- - i.

executed. For an attention message, the simulated operation V is carried out on the semaphore G "» D_. The system name G- _f D. thus identifies the semaphore to which all messages linked to the channel program are to be fed. The system name G , D ^ identifies

3 a

draws the semaphore, which contains all messages linked to a certain peripheral device are to be supplied.

The q / lc / EVQ queue was previously described and it contains all input / output messages during the execution of the previous instruction. The queue Q / LC / FLS is formed by the event query system during the execution of a simulated operation V in favor of the digital channel LC if it does not find a process waiting for the appropriate semaphore and if there is no free communication link in the semaphore FLS of the segment containing the appropriate semaphore SD finds. These connection fields

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are provided in word 8 or in word 12 of an input LCTE and they identify - the relative position of the digital channel table entry based on the header identifier, which is supplied by the predetermined positions 2 E and 2 F of the working memory. If that Head identifier no following connection field indicates, i.e. if his head of the queue is zero, then this indicates that there is no entry in the queue is. These queues Q / LC / EVQ and Q / LC / FLS are the messages queuing in Q / M / S and the Process connection queues Q / PL / PLS analog. These snakes differ in that the Queue Q / LC / FLS contains those messages originating from the queue Q / LC / EVQ that not at their assigned semaphores (G-, D.)

or (G ", Dl can be classified because in a a

the corresponding segments SD free connections are missing. This can be seen in more detail from the in Fig. 19 shown flow chart.

In the flow chart in FIG. 19, the first table entry LCTE removed from queue Q / LC / EVQ in phase 101. It's an input in the position 2 F of the main memory SPU, which identifies the head of the queue Q / LC / EVQ. This input is thus an identifier of the first entry LCTE in the queue. This absolute address becomes the Position 2 E is taken and its address is used to access the first digital channel table entry used. The identifier has been brought into the working memory as the asynchronous one The input / output subsystem put a message on the queue.

509832/0921

In phase 102 the question is asked whether it is a warning event. if that is the case, in phase 103 the

Address G, D of the semaphore to which the Nacha a

reht is taken from the input LCTE. If it is not a warning message is, in phase 104 the name G., D. of the semaphore to which the message is forwarded is taken from word 14 of the input LCTE.

In phase 105 the first input LCTE of the queue Q / LC / EVQ is output from the queue, by changing the memory location to display a new header of the LCTE table, and the following connection field of the input LCTE is taken. The table entry LCTE is has thus been removed and your message is to be brought to the message semaphore, which is indicated by the system name GD. In phase 106 the message is in the positions WC 4 brought to WC 7 of the working memory. If it is an intermediate message, words 3 through 11 are in these positions transmitted, whereas if it is an attention message, the words 12 * f by 3pm to be brought there.

In phase 107 the message is transmitted to the appropriate semaphore identified by the System name is specified by means of a simulated operation V. At the end of operation V, the Event query system reintroduced and the following input LCTE, if there is one, will be transferred there.

509832/0921

The flow chart 19 is thus a summary of the operations that can be performed with an event reporting message executed when communication with a process of the central processor is required is.

Recall that an instruction V is an issue operation which allows a message to an intermediate point called a semaphore. The semaphore stores the Data until a process is ready to extract it. Before that, the command V is through the process which controls the central unit. A simulated operation V is almost with the instruction V in the sense that they are information about another process or about another Group of processes in the central processor sends. It differs from the command V in that the process controlling the central processor is a pseudo process, i. the event query system or the central facility for the exceptions, which executes the command. That Event Query System is a part of the firmware block that acts as a request manipulator or stage for processing the requests (request handler) is designated. This part deals with all events that occur. Likewise, the facility for processing the Exceptions (exception handler) with all exceptions.

The main peculiarities of the simulated operation V, initiated by the event query system we are:

1) Update the digital channel condition after the successful passage of the message, in contrast

509832/0921

to update the state of the process, which has been executed by the process controlled by the central processor.

2) queuing the digital channel to Q / LC / FLS if there is no waiting process at the appropriate one Semaphore has been found.

3) checking the G field of the semaphore of free connections in the relevant segment SD if the counting field CCT of the digital channel is below O is. . .

In addition, two additional differences have been provided for the input / output event. The first difference is the content of the items delivered and transmitted by the simulated operation V. News.

The content of the message for the input / output interruption has been described with reference to Fig. 18 in the course of the description of the table LCTE. Second, the address of the semaphore can have two names, ie a local name SEG, SRA and a system name G _e D. It should be remembered that the name SEGi SRA was used to identify the semaphore for the control process of the central processor. · A system name GD is also provided, as has already been specified for the termination and warning intermediate messages.

The system name of a semaphore is the address GD of the semaphore in the corresponding segment SD.

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Addressed to the semaphores G. D. and G D

News.

During the execution of a channel program, various intermediate messages PEN can be sent via the Reporting of events and an end message TEN are sent out.

In the meantime, there is only a single zone in the associated digital input LCE, which is the temporary Entry of these messages enabled (words 8 to B) 16.

An analogous situation exists for the messages about the reporting of warning events (AEN). There is a single storage zone for this Messages in input LCE (words C through F). A message can occupy a zone while a subsequent message is presented to the same zone.

a) if this message from the device control PCU has been sent, the control unit IOC will respond with a command STACK to the message in a stack and in order to indicate the presence of a stack in the digital channel input LCE to specify. As a result, when the original message is taken from the LCE input, the STACK state detected. As a result, the control unit IOC issues an UNSTACK to the device control PCU, which transmits the message contained in the stack.

b) if this message has been issued by the control unit IOC, it is the previous one Message deleted and lost. The only action that will be taken is that the new message indicates that the

509832/0 9 21

previous one has been lost.

Multiplexing the Spatial Channels Six spatial channels can be connected to the input / output controller IOC, for example. They are numbered from 0 to 5. Different channel programs can be executed simultaneously on different spatial channels. The organization of this simultaneity is carried out by the control unit IOC and by the microprograms assigned to it. The IOC control unit distinguishes between two types of information processing:

- the processing of service code groups.

- the processing of the transmissions of data or detailed states.

Each type of processing has a high or low level of urgency.

Urgent-

Processing level Number of the level

Transfer of data or

States high O

Service code groups to the power of 1

tJ transfer of data or

States low 2

Service Code Groups Low 3

All these types of processing have an urgency, which is greater than the urgency of the operations of the central processor that the Have urgency level 4.

If at a given point in time different spatial channels processings on different

509832/0921

Require levels of urgency, an urgency body chooses to work with higher levels of urgency Urgency and makes the others wait.

If different channels request processing in the same way, but on the same Urgency level, the urgency system of the input / output control unit IOC selects the spatial one Lowest numbered channel and let the others wait.

If at a certain point in time a processing for a spatial channel for the central processing unit CPU arrives and when the emergency system of the control unit IOC another work with higher Selects urgency, an interrupt occurs which interrupts the processing of those in progress Interrupts work and replaces it with new work. The interrupted work will be restored recorded when the new job is finished. The tasks are therefore interrupted one after the other and resumed in order of urgency if the task is of utmost urgency has ended.

The IOC firmware consists of a certain number of microprogram blocks corresponding to the different levels of urgency of the processing carried out by the control unit IOC.

The interruptions of microprograms due to the change in the programs made by the control unit IOC tasks performed are the IOC interrupts.

Fig. 21 shows the execution of the processing of

509832/09 21

Operations on the three spatial channels PCO, PC1 and PC2.

The time is plotted on the abscissa and the sequence when executing a channel program is represented by a thick line. In this figure, the central processor performs in a first Processing at urgency level 4. Thereafter, the spatial channel PC 1 has one Perform input / output at level 3 (low-speed transmission of service code groups) . The central processor CPU is interrupted and operations are carried out on the Channel PC 1 executed until a service code group transfer request at level 1 (high - speed) appears, which is delivered by the PCO channel. The one on channel PC 1 in execution operation is interrupted until the operation on the PCO channel is finished » Then the processor finishes the operation of the channel PC 1 at stage 3 and begins one Operation on Kana.1 PC 2 also with level 3, which is performed by an operation on the channel PCO with level 0 (high-speed data transmission) is interrupted, etc. The input / output operations will continue until there is no more information to point to the Channels are to be transmitted. The central processor then takes its processing at level 4 back on.

The urgency level is defined in the device control PCU by means of a code group. In one episode of service code groups that are output from the device control PCU to the control unit IOC

509832/09 21

the first octad is always the service code group. One bit of this service code group (for example the last) indicates the level of urgency. If it has a digital value of 1, it is acting a high urgency, and if it has a digital value of zero, a low one Urgency.

When the sequence of the service code group begins a transmission of data or a detailed .Stands forms, one or two more bits of the service code group indicate the urgency level at.

The service code groups concerned are:

- Start of data transmission 1

- Beginning of a transmission of a detailed f state

- Shifting of the channel program pointers: Bits 4 and

The input / output control unit just described controls the transfers of data and service code groups between the Central memory and at least one device control. The new features of their structure form the subject of the patent application filed at the same time by the same applicant: "Arrangement for controlling the transmissions of data between the central memory and the peripheral units of a data processing system " (Priority of the French patent application 74 03 488).

The input / output control unit according to the invention has the advantage that the information transfer times

509832/0921

can be reduced to the minimum by the events occurring v / ie pseudoprocesses are processed. These can be informed at any moment about the occurrence of synchronous or asynchronous events by sending messages placed on semaphores.

Of course, the present invention is not limited to the embodiment described above limited. Within the scope of the invention, the person skilled in the art has numerous possible modifications.

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Claims (11)

Patent claims: Input / output control unit for controlling data transfers between the central unit and at least one system of peripheral devices connected to a device controller which is connected to the central unit via a spatial channel, characterized in that that the operations are controlled by channel programs which are made out in memory Contained words for the control of basic operations exist that refer to the spatial channel related information in an input of the associated with a table of spatial channels spatial channel is that the information relating to a peripheral device are combined in a digital channel entry belonging to a table of digital channels, and that the transition to the execution state of a channel program under the control of an instruction by connecting it to a digital channel input, the digital channel then put on an execution queue. 2. Input / output control unit according to claim 1, characterized in that a queue each of the named spatial channels is assigned that the queue the channel programs according to levels of urgency and within one and the same level according to the order of arrival and that a signal has the digital value as long as the queue has at least one to be executed Contains channel program. 509832/0921 3. Input / output control unit according to claim 1 and 2, characterized in that the device control controls the data transfers by it outputs to the input / output control unit a service code group which allows the to be taken from the queue as the first digital channel to be executed and from the device control to respond by giving them the digital channel number which has been taken from the digital channel input and the first channel command input is. 4. Input / output control unit according to the claims 1 to 3, characterized by two channel program pointers, one of which points to the first control word the first channel command input and the second refer to the second control word or to the ", first control word of the following channel command input, the execution of the channel program is achieved by shifting the pointers. 5. Input / output control unit according to the preceding Claims, characterized by devices that control the device events report and receive the event reporting messages, with the transmission of information being interrupted and the messages in one of the two zones of the digital channel entry or in a zone of the spatial channel are stored and with the messages summarized states of the device control and the input / output control unit, parameters relating to the execution of the channel programs and the purpose of the message. 509832/09 21 6. Input / output control unit according to the preceding claims, characterized in that the event notification messages are organized in a queue - (Q / MS / EVQ) in the order of their arrival, then removed from the queue in the same order in which they have been entered, and are arranged on one of three semaphores (G- D _a , G .. D., GD) depending on the type of message, the memory areas are extracted and associated with a process waiting on the corresponding semaphore. 7. Input / output control unit according to claim 6, characterized in that in the case of intermediate events or Attention-Events the messages that are not placed on one of the aforementioned semaphores semaphores of free connections to form a new queue (Q / LC / FLS) with the messages remaining in the memory areas of the digital channel table entries. 8. Input / output control unit according to claim 6, characterized in that in the case of a channel exception message the message from the queue (Q / MS / EVQ) and storage zone of the input of the spatial channel taken, abandoned by the event interrogation device and by the device for Processing of exceptions is included. 9. Input / output control unit according to claim 6 and 7, characterized in that when one of the connections of semaphores (GD or G ₌ D) becomes free, 11 α a transmit a message from the queue (Q / LC / FLS) to the corresponding semaphore and the Storage zone of the corresponding digital channel entry 509832/0 9 21 -113 - " is removed. 10. Input / output control unit according to one of the preceding claims, characterized by means of decoding information related to the stage and the The type of transfer to be carried out and transferred by the device control, and by an urgency circuit controlled by the information, which enables the execution of the Transmission that has a higher priority is permitted and interrupt the other transmissions. 509832/0921